Question: What is $42\%$ of $50$ ?
Explanation: Having $42\%$ of something means that you get $42$ out of every $100$ We can set up a proportion to find out what number is $42\%$ of $50$ $ \dfrac{{\text{percent}}}{100} = \dfrac{{\text{part}}}{{\text{whole}}}$ Which things do we know, and what are we trying to find? We know the ${\text{percent}}$ is $42$ . Is $50$ the ${\text{part}}$ or the ${\text{whole}}$ The $50$ is the ${\text{whole}}$ . We are trying to find the ${\text{part}}$ that makes up $42\%$ of it: $ \dfrac{{42}}{100} = \dfrac{{\text{part}}}{{50}}$ If we divide the denominator of the fraction on the left by $2$ , it will be the same denominator of the fraction on the right. To keep things equal, let's also divide the numerator on the left by $2$ $ \dfrac{{42} \div 2}{100 \div 2} = \dfrac{{\text{part}}}{{50}}$ $ \dfrac{{21}}{50} = \dfrac{{\text{part}}}{{50}}$ $ {21} = {\text{part}}$ So $21$ is $42\%$ of $50$.